Interior Design

DNA and its complex specified information

Thanks to the hit show CSI, we've heard a lot about DNA lately. Found in a stray hair and used to prove a killer's identity, this mysterious "genetic fingerprint” can bring any case to a satisfying conclusion in just one episode. However, this tiny molecule is far more than a convenient plot device; it's the blueprint that stores nearly all the information your body needs to grow and run. In fact, all the complexity of life on earth depends on its information-carrying DNA. Yours is unique just as you are unique, for it played no small role in making you.

Much like the letters in a sentence, DNA is made up of many smaller molecules strung together in a precise sequence. Though it can be arranged in any order, a random one will no more make a viable organism than random English letters will make poetry. Only those sequences that correspond to the "genetic code” can be read as plans for the protein "machines” that power our cells. This information is essential to life as we know it, but where did it come from?

That question brings focus to a debate that's raged since Charles Darwin: Life, like poetry, appears designed, but is it? Darwinists claim it's merely the product of a long series of lucky accidents, sorted by the grim reaper ("natural selection”). But such evolution is something only reproducing life can do, and DNA is what gives life the ability to reproduce its vital information. It is therefore unclear how information-carrying DNA itself could have evolved. There are more theories than crime dramas on CBS, but few are as realistic.

For this and other reasons, a growing number of scientists are rejecting the Darwinian claim that life is an accident. Intelligent design theorists note that DNA, as well as the protein machines it codes for, possesses "complex specified information” (abbreviated, coincidentally, CSI). This means it is both highly improbable (complex) and conforms to an independent pattern (specified). Design theorists argue that this failure to find a viable non-intelligent explanation for life's information should not surprise us; for in our experience, CSI is always the product of intelligence.

An illustration will clarify: Imagine finding "I love you” scribbled on a deserted beach. A Darwinist might stand there wondering what unknown natural process produced the message, but most of us would conclude that someone had written it. Why would we think this without any direct evidence? Not because marks in the sand are themselves impossible for natural processes to produce; a mass of sticks in the tide might do it. And not because of the sheer improbability of the arrangement itself, for any other would be equally unlikely. We infer design because this improbable arrangement conforms to an independent pattern. Since the English language does not determine the movement of sticks in the tide, the possibility that they would just happen to produce "I love you” is not just remote; it's irrelevant. We recognize that this kind of specified complexity is always the product of design. An alternate explanation might exist (imagination is free, after all), but only an illiterate brute would fail to recognize design as the most logical explanation of a message in the sand.

What does this have to do with DNA? It, too, expresses a highly improbable arrangement (in its molecular sequence) that conforms to an independent pattern (the genetic code). In fact, complex specified information is precisely what makes it useful to life on earth at all. If there's a problem with the illustration, it's that it's too simple. The DNA sequence of even the lowliest bacterium would fill a hefty volume if written out in English characters (yours, assuming you're a human being, could fill a million pages). If life's essential information were really like a message in the sand, the full text of Romeo and Juliet would be a closer analogy. In everyday life, we routinely infer design based on far less CSI than this; should we not conclude the same here?

Many scientists say no. Why? It's not that they doubt intelligent designers can produce CSI, for every word they write proves we can. Nor is it because they have a better explanation for its origin—decades of study have produced many intriguing ideas but only skirted this central issue. It's not because of its explanatory value that design is rejected. It's because its implications for the nature of science itself make people nervous. If we started appealing to design whenever we didn't understand something, science would never get anywhere.

Nevertheless, design can be a live possibility without becoming a cover for ignorance. For this very reason, design theorists have laid out strict criteria and focused only on cases of immense specified complexity (sadly, "I love you” wouldn't make the cut). Darwinists may find it convenient to caricature these theorists as backwards-looking naval gazers, but intelligent design is simply the best and only explanation we have for the origin of complex specified information. Any theory can be abused and misapplied, but until or unless someone has a better explanation for CSI, it is foolish to reject out of fear the only one we have.

In any case, science can recognize life's information as the product of intelligence without ending its search for an explanation. To identify something as designed is to say it exists for a purpose and would not exist otherwise.

How that purpose was carried out is a separate question, and the answer may involve any number of secondary causes or processes. A book is not less designed when produced by an automated printing press than when written by hand, and it's valid to ask which method was used. Likewise, the realization that life's CSI points to design need not prevent us from investigating whether any non-intelligent processes were involved in its history. Design may even be compatible with common descent and evolution by natural selection. It merely sets these processes in a broader framework and explains what they never could: the origin of specified complexity.

In short, design theory is a simple inference to the best explanation, and the danger of abuse should not negate its scientific value. However, it does raise questions science simply cannot answer. An investigation of a love note at the beach might tell you how it was written—with a stick, a big toe, or a complicated machine designed especially to inscribe sonnets in the sand—but that by itself won't tell you who wrote it. Similarly, if we can know anything about the designer behind life's specified complexity, it will take more than empirical observation to discover it. Design, like love, carries us to the ragged edge of science. But that's hardly reason to reject it. Indeed, the same is true of Darwinism, which is no small part of why this debate has remained heated for 150 years.

Good science has always answered one question by uncovering a deeper one, and design theory is no exception. If this risks leading us back to the very deepest mysteries of all—why are we here? what is our purpose?—is that a shortcoming, or a triumph? •

Maker's Marks

Darwinists attempt to explain specified complexity by breaking it into parts simple enough to arise by chance and capable of building up slowly over time. In nature, we have never observed this process to accomplish anything more than minor improvements to existing structures. But in computer science, so called "evolutionary algorithms” have produced results that seem to exceed the ability of their programmer (checkers-playing programs that beat world champions, for instance).

Nonetheless, since these algorithms themselves must be carefully designed, their results—however impressive—would not have come about apart from intelligence. The core of the program that makes evolution possible and gives it a goal cannot itself evolve from nothing. Evolution, therefore, may be able to adapt and improve specified complexity, but itself seems to depend on prior design.

1 DNA is pictured in two different ways. On the right is a model of an actual string of DNA. On the left is a schematic drawing indicating the different molecules (identified A, T, G, and C) that, when arranged in precise sequences, give DNA the ability to store information. Cells use the "genetic code” to translate these sequences into the specific proteins they need to survive. This is necessary because DNA can be copied and passed on to one's offspring, while proteins cannot.

2 Most of life's basic operations—from processing food to transferring signals in the brain—are performed by one or more specific proteins. The bacterial flagellum (pictured here) is a well-known example. This tiny "molecular machine” is essentially a powered rotor built of dozens of proteins in a precise arrangement. It is DNA that allows our cells to properly sequence these and all the other proteins vital to our survival.